Hollow-core fiber cable and method of manufacturing the same

ABSTRACT

The invention generally relates to optical fibers, and, more particularly, to hollow-core optical fibers and cables for use in high-speed data transmission, including transmission of telecommunications data, and methods of manufacturing such hollow-core optical fibers and cables.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S.Provisional Application No. 62/975,420, filed on Feb. 12, 2020, thecontent of which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention generally relates to optical fibers, and, moreparticularly, to hollow-core optical fibers and cables for use inhigh-speed data transmission and methods of manufacturing suchhollow-core optical fibers and cables.

BACKGROUND

Modern communication systems increasingly rely upon fiber optic networksto carry large amounts of data between sites, as optical fibers permittransmission over longer distances and at higher bandwidths (data rates)than conventional electrical cables. Optical fibers are used instead ofconventional metal wires because signals travel along optical fiberswith less attenuation (transmission loss), and, in many instances,optical fibers are immune to electromagnetic interference, a drawbackassociated with the use of metal wires. As such, fiber optics technologyplays a critical role within the telecommunications sector, due in largepart to the wide-scale and growing adoption of the technology incommunication and data transmission services.

Traditional optical fibers include flexible, transparent fibers made bydrawing glass (silica) (or plastic) to a diameter slightly thicker thanthat of a human hair. An optical fiber typically includes a coresurrounded by a cladding material with a lower index of refraction.Light is kept within the core by a phenomenon known as total internalreflection, which causes the fiber to act as a waveguide responsible forguiding light within the fiber. In particular, the higher-index coresurrounded by the lower-index cladding is a geometry that results in thetotal internal reflection of radiation entering the fiber over a selectrange of angles.

The use of optical fibers for communication (i.e., transmittinginformation from one place to another) involves sending pulses ofinfrared light through such optical fibers. The light forms anelectromagnetic carrier wave that is modulated to carry certaininformation (e.g., data). The two most commonly used transmissionwavelength windows or bands with the lowest values of attenuationconsist of a 1310 nm (nanometer) wavelength band, with a minimum loss ofapproximately 0.4 dB/km (decibel/kilometer), and a 1550 nm wavelengthband, with a minimum attenuation of approximately 0.2 dB/km.

As a result of the lower loss and corresponding reduction in lineamplification required, manufacturers have begun focusing on devices andfibers to support operation at around the 1550 nm wavelength. Whilethere has been a trend to move toward transmission of data in the 1550nm wavelength band, many communications systems continue to rely on the1310 nm wavelength band for the communication and transmission ofcertain information, as the cost of manufacture of 1310 nm devices andfibers is much less than that of 1550 nm devices and fibers. However,conventional optical fibers, particularly for use in the 1310 nmwavelength band, suffer drawbacks. For example, some communicationssystems rely on solid-core fiber optics, wherein such optical fibers maysuffer from low bandwidth capabilities, resulting in less than optimaldata transmission and undesired latency, which is particularlyburdensome in systems that require high-speed data transmission.

SUMMARY

The present invention recognizes the drawbacks of current fiber opticsand provides a hollow-core optical fiber and cable configured to addresssuch drawbacks. In particular, aspects of the invention are directed toa hollow-core optical fiber configured to support and guide thepropagation of light at a wavelength of 1310 nm (nanometers) and methodsof forming such a hollow-core optical fiber.

The hollow-core optical fiber includes a microstructured cladding regionsurrounding a hollow core region. The geometry of the hollow core andmicrostructured cladding regions enables the optical fiber to supportand guide the propagation of light at a wavelength of 1310 nm. Morespecifically, unlike the solid-core optical fibers, which rely on asolid core having a higher refractive index than the surroundingcladding material in order to form the total internal reflectionstructure, the hollow-core optical fiber structure is configured toguide optical energy within the hollow core region by total internalreflection at an interface between the hollow core region, having alower refractive index, and the microstructured cladding region, havinga higher refractive index. The hollow-core optical fiber structureallows for the guidance of optical energy (i.e., light) withoutsignificant leakage or loss of signal that may normally occur withsolid-core optical fibers. In particular, a majority (at least 99%) ofthe light transmitted by the hollow-core optical fiber travels in air(or other gas), providing such a fiber with a unique set of transmissionproperties, including lower non-linearity and lower latency whencompared to the properties of solid-core optical fibers.

The present invention further provides a fiber optic cable, whichincludes at least one hollow-core optical fiber, configured to be usedwith a fiber optics network of a communications system for thetransmission of telecommunications data. For example, the fiber opticcable may include at least one hollow-core optical fiber encased withina cable housing and optical fiber connectors coupled to ends of thehollow-core optical fiber and configured to operably receive andtransmit light at a wavelength of 1310 nm. The optical fiber connector,for example, may include a small form factor (SFF) connector configuredto mechanically couple the hollow-core optical fiber to at least one ofan additional optical fiber and/or a device for transmitting and/orreceiving a light signal (e.g., communications equipment or the like).

Accordingly, by providing a hollow-core optical fiber able to functionwithin the 1310 nm optical wavelength band, the benefits of hollow-coreoptical fibers can be realized in communication systems operating withinthe 1310 nm optical wavelength band. More specifically, the hollow-coreoptical fiber of the present invention would reduce latency andattenuation when used in telecommunications networks and applications,thereby enhancing the speed and distance capabilities beyond currentdesigns engineered around solid-core optical fibers. Furthermore, thefiber optic cable allows for the hollow-core optical fiber to be usedwith commercially available communications equipment (e.g., radios,switches, SFP Modules, etc.), and provide the advantages of ahollow-core optical fiber over the conventional solid-core opticalfibers.

Certain aspects of the invention relate to a hollow-core optical fiberconfigured to support and guide the propagation of light at a wavelengthof 1310 nm. The hollow-core optical fiber includes a microstructuredcladding region and a hollow core region surrounded by themicrostructured cladding region and configured to guide optical energywithin the hollow core region by total internal reflection at aninterface between the hollow core region and the microstructuredcladding region. The hollow core and microstructured cladding regionsare configured to support and guide the propagation of light at awavelength of 1310 nm.

In some embodiments, at least the hollow core region comprises a gas ora vacuum. For example, the hollow core region may include air. In someembodiments, the hollow core region includes a lower refractive indexand the microstructured cladding region includes non-coaxial regions ofhigher refractive index. The microstructured cladding region comprises acladding material. In some embodiments, the cladding material ispositioned substantially symmetrically around the hollow core region.For example, the cladding material may be arranged in a regularly spacedperiodic array. In some embodiments, the periodic array may beconfigured in a polygonal lattice pattern. For example, the periodicarray may be configured in a hexagonal lattice pattern.

Other aspects of the invention relate to a method of fabricating ahollow-core optical fiber. The method includes assembling and forming apreform of plurality of elongate elements, at least some of the elongateelements comprising capillaries, and drawing the preform into ahollow-core optical fiber configured to support and guide thepropagation of light at a wavelength of 1310 nm. The fabricatedhollow-core optical fiber includes a microstructured cladding region anda hollow core region surrounded by the microstructured cladding regionand configured to guide optical energy within the hollow core region bytotal internal reflection at an interface between the hollow core regionand the microstructured cladding region. The hollow core andmicrostructured cladding regions are configured to support and guide thepropagation of light at a wavelength of 1310 nm.

In some embodiments, at least the hollow core region comprises a gas ora vacuum. For example, the hollow core region may include air. In someembodiments, the hollow core region includes a lower refractive indexand the microstructured cladding region includes non-coaxial regions ofhigher refractive index. The microstructured cladding region comprises acladding material. In some embodiments, the cladding material ispositioned substantially symmetrically around the hollow core region.For example, the cladding material may be arranged in a regularly spacedperiodic array. In some embodiments, the periodic array may beconfigured in a polygonal lattice pattern. For example, the periodicarray may be configured in a hexagonal lattice pattern.

Other aspects of the invention relate to a hollow-core optical fiberconfigured to support and guide the propagation of light at a wavelengthof 1310 nm and an optical fiber connector coupled to both ends andconfigured to operably receive and transmit light at a wavelength of1310 nm. The optical fiber connector may include a small form factor(SFF) connector configured to mechanically couple the hollow-coreoptical fiber to at least one of an additional optical fiber and adevice for transmitting and/or receiving a light signal. The hollow-coreoptical fiber includes a microstructured cladding region and a hollowcore region surrounded by the microstructured cladding region andconfigured to guide optical energy within the hollow core region bytotal internal reflection at an interface between the hollow core regionand the microstructured cladding region. The hollow core andmicrostructured cladding regions are configured to support and guide thepropagation of light at a wavelength of 1310 nm.

In some embodiments, at least the hollow core region comprises a gas ora vacuum. For example, the hollow core region may include air. In someembodiments, the hollow core region includes a lower refractive indexand the microstructured cladding region includes non-coaxial regions ofhigher refractive index. The microstructured cladding region comprises acladding material. In some embodiments, the cladding material ispositioned substantially symmetrically around the hollow core region.For example, the cladding material may be arranged in a regularly spacedperiodic array. In some embodiments, the periodic array may beconfigured in a polygonal lattice pattern. For example, the periodicarray may be configured in a hexagonal lattice pattern.

Other aspects of the invention relate to a fiber optic cable. The fiberoptic cable includes at least one hollow-core optical fiber configuredto support and guide the propagation of light at a wavelength of 1310 nmand at least one optical fiber connector coupled to both ends of thehollow-core optical fiber and configured to operably receive andtransmit light at a wavelength of 1310 nm. The fiber optic cable furtherincludes a cable housing encasing at least the hollow-core optical fiberwithin. The cable housing may include a durable and robust materialconfigured for at least outdoor use. The optical fiber connector mayinclude a small form factor (SFF) connector configured to mechanicallycouple the hollow-core optical fiber to at least one of an additionaloptical fiber and a device for transmitting and/or receiving a lightsignal.

In some embodiments, the hollow-core optical fiber includes amicrostructured cladding region and a hollow core region surrounded bythe microstructured cladding region and configured to guide opticalenergy within the hollow core region by total internal reflection at aninterface between the hollow core region and the microstructuredcladding region. The hollow core and microstructured cladding regionsare configured to support and guide the propagation of light at awavelength of 1310 nm.

In some embodiments, at least the hollow core region comprises a gas ora vacuum. For example, the hollow core region may include air. In someembodiments, the hollow core region includes a lower refractive indexand the microstructured cladding region includes non-coaxial regions ofhigher refractive index. The microstructured cladding region comprises acladding material. In some embodiments, the cladding material ispositioned substantially symmetrically around the hollow core region.For example, the cladding material may be arranged in a regularly spacedperiodic array. In some embodiments, the periodic array may beconfigured in a polygonal lattice pattern. For example, the periodicarray may be configured in a hexagonal lattice pattern.

Other aspects of the invention relate to a method of transmittingtelecommunications data. The method includes providing a hollow-coreoptical fiber configured to support and guide the propagation of lightat a wavelength of 1310 nm, receiving a light signal comprisingtelecommunications data, and transmitting, via the hollow-core opticalfiber, the light signal.

In some embodiments, the hollow-core optical fiber includes amicrostructured cladding region and a hollow core region surrounded bythe microstructured cladding region and configured to guide opticalenergy within the hollow core region by total internal reflection at aninterface between the hollow core region and the microstructuredcladding region. The hollow core and microstructured cladding regionsare configured to support and guide the propagation of light at awavelength of 1310 nm.

In some embodiments, at least the hollow core region comprises a gas ora vacuum. For example, the hollow core region may include air. In someembodiments, the hollow core region includes a lower refractive indexand the microstructured cladding region includes non-coaxial regions ofhigher refractive index. The microstructured cladding region comprises acladding material. In some embodiments, the cladding material ispositioned substantially symmetrically around the hollow core region.For example, the cladding material may be arranged in a regularly spacedperiodic array. In some embodiments, the periodic array may beconfigured in a polygonal lattice pattern. For example, the periodicarray may be configured in a hexagonal lattice pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary fiber optic cable including ahollow-core optical fiber consistent with the present disclosure.

FIG. 2 is an enlarged view of the fiber optic cable of FIG. 1illustrating components of the cable in greater detail.

FIG. 3 is an enlarged view of the fiber optic cable of FIG. 1illustrating the hollow-core optical fiber and optical fiber connectorsin greater detail.

FIG. 4 is a cross-sectional view of an exemplary hollow-core opticalfiber consistent with the present disclosure.

FIG. 5 is an enlarged view of a cross-section of the hollow-core opticalfiber illustrating the geometry of the hollow core region andsurrounding microstructured cladding region in greater detail.

FIG. 6 shows a preform of a plurality of elongate elements in the formof capillaries suitable for use in forming a hollow-core optical fiberconsistent with the present disclosure.

FIG. 7 illustrates and exemplary apparatus for use in fabricating ahollow-core optical fiber from the preform illustrated in FIG. 6 .

FIG. 8 is a block diagram illustrating a fiber optics network includinga hollow-core fiber optic cable consistent with the present disclosure.

FIG. 9 is a flow diagram illustrating one embodiment of a method fortransmitting telecommunications data utilizing the hollow-core opticalfiber.

DETAILED DESCRIPTION

The present invention is directed to hollow-core optical fibers andcables for use in high-speed data transmission, including transmissionof telecommunications data. In particular, aspects of the invention aredirected to a hollow-core optical fiber configured to support and guidethe propagation of light at a wavelength of 1310 nm and methods offorming such a hollow-core optical fiber.

The hollow-core optical fiber includes a microstructured cladding regionsurrounding a hollow core region. The geometry of the hollow core andmicrostructured cladding regions enables the optical fiber to supportand guide the propagation of light at a wavelength of 1310 nm. Morespecifically, unlike the solid-core optical fibers, which rely on asolid core having a higher refractive index than the surroundingcladding material in order to form the total internal reflectionstructure, the hollow-core optical fiber structure is configured toguide optical energy within the hollow core region by total internalreflection at an interface between the hollow core region, having alower refractive index, and the microstructured cladding region, havinga higher refractive index. The hollow-core optical fiber structureallows for the guidance of optical energy (i.e., light) withoutsignificant leakage or loss of signal that may normally occur withsolid-core optical fibers. In particular, the hollow-core optical fiberreduces attenuation as compared to the solid-core optical fibers due tothe fact that most of the radiation loss in a solid-core optical fiberoccurs from absorption in the solid core. In particular, a majority (atleast 99%) of the light transmitted by the hollow-core optical fibertravels in air (or other gas), providing such a fiber with a unique setof transmission properties, including lower non-linearity and lowerlatency when compared to the properties of solid-core optical fibers.

The present invention further provides a fiber optic cable, whichincludes at least one hollow-core optical fiber, configured to be usedwith a fiber optics network of a communications system for thetransmission of telecommunications data. For example, the fiber opticcable may include at least one hollow-core optical fiber encased withina cable housing and optical fiber connectors coupled to ends of thehollow-core optical fiber and configured to operably receive andtransmit light at a wavelength of 1310 nm. The optical fiber connectormay include a small form factor (SFF) connector configured tomechanically couple the hollow-core optical fiber to at least one of anadditional optical fiber and/or a device for transmitting and/orreceiving a light signal.

Accordingly, by providing a hollow-core optical fiber able to functionwithin the 1310 nm optical wavelength band, the benefits of hollow-coreoptical fibers can be realized in communication systems operating withinthe 1310 nm optical wavelength band. More specifically, the hollow-coreoptical fiber of the present invention would reduce latency andattenuation when used in telecommunications networks and applications,thereby enhancing the speed and distance capabilities beyond currentdesigns engineered around solid-core fiber. Furthermore, the fiber opticcable allows for the hollow-core optical fiber to be used withcommercially available communications equipment (e.g., radios, switches,SFP Modules, etc.), and provide the advantages of a hollow-core opticalfiber over the conventional solid-core optical fibers.

FIG. 1 illustrates an exemplary fiber optic cable 10 consistent with thepresent disclosure. FIGS. 2 and 3 are enlarged views of the fiber opticcable 10 illustrating components of the cable in greater detail. Thefiber optic cable 10 includes a cable housing or outer jacket 12, atleast one hollow-core optical fiber 14 housed or encased within thecable housing 12, and one or more optical fiber connectors 16 coupled toa respective end of the hollow-core optical fiber 14. For example, asshown, a first optical fiber connector 16 a is coupled to a first end 15a of the hollow-core optical fiber 14 and a second optical fiberconnector 16 b is coupled to a second end 15 b of the hollow-coreoptical fiber 14. The fiber optic cable 10 may include any number ofoptical fibers 14. For example, as illustrated, the cable 10 includestwo separate hollow-core optical fibers.

The cable housing 12 may be coupled to the hollow-core optical fiber 14by any known means (i.e., adhesive, coated, compressive fit, mechanicalcoupling, or the like). Furthermore, the cable 10 may include transitioncomponents along portions of the respective ends 15 a, 15 b of the fiber14 so as to effectively expose or make a respective end of the fiberavailable for connection with either another optical fiber orcommunication devices or equipment, such as ferrules 13 or the like. Thecable housing 12 may include one or more layers of durable and robustmaterials providing insulative and/or protective properties. Forexample, in one embodiment, the cable housing 12 may include apolyethylene (PE) material resistive to moisture and sunlight exposure,thereby allowing for the fiber optic cable 10 for outdoor use, inaddition to indoor use.

As previously described herein, the hollow-core optical fiber 14 isconfigured to support and guide the propagation of light at a wavelengthof 1310 nm. It should further be noted that the optical fiber connectors16 a, 16 b are configured to operably receive and transmit light at awavelength of 1310 nm. For example, the optical fiber connectors 16 a,16 b may include a small form factor (SFF) connector configured tomechanically couple the hollow-core optical fiber 14 to at least one ofan additional optical fiber and a device for transmitting and/orreceiving a light signal (i.e., communications equipment or the like).Accordingly, the fiber optic cable 10 is configured to be used with afiber optics network of a communications system operating within the1310 nm optical wavelength band.

FIG. 4 is a cross-sectional view of an exemplary hollow-core opticalfiber 14 consistent with the present disclosure. As shown, the fiber 14includes a microstructured cladding region 18 and a hollow core region20 surrounded by the microstructured cladding region 18. The opticalfiber 14 is configured to guide optical energy within the hollow coreregion 20 by total internal reflection at an interface between thehollow core region 20 and the microstructured cladding region 18. Morespecifically, the hollow core region 20 and microstructured claddingregion 18 are configured to support and guide the propagation of lightat a wavelength of 1310 nm.

FIG. 5 is an enlarged view of a cross-section of the hollow-core opticalfiber 14 illustrating the geometry of the hollow core region 20 andsurrounding microstructured cladding region 20 in greater detail. Asused herein, a core is a physical feature having a structure that causeslight to be propagated substantially within its boundary. The hollowcore region 20 comprises a hollow core formed as an enlarged hole at thecenter of the microstructured cladding region 18. The hollow core may beformed as a hole in the material of the microstructured cladding, or maybe formed as a hole in a different material. Light propagating in thefiber 14 is confined substantially to the hollow core region 20. Itshould be noted that, while only a single hollow core region isillustrated in figures herein, optical fibers consistent with thepresent disclosure may include multiple hollow core regions.Furthermore, while it may be preferable that the hollow core of theoptical fiber 14 be located along the central axis of the fiber 14, thecore(s) may be located at position(s) other than along the central axisof the fiber 14.

The microstructured cladding region 18 comprises a cladding material,generally in the form of elongate elements, at least some of whichinclude capillaries 22, such as silica capillaries. The capillaries 22are positioned substantially symmetrically relative to the hollow coreregion 20, wherein the hollow core region 20 is formed, for example, byomission of one or more capillaries 22 from a preform of the fiber 14,as will be described in greater detail herein. For example, asillustrated, the capillaries are arranged in a regularly spaced periodicarray configured in a polygonal lattice pattern, specifically ahexagonal lattice pattern. However, it should be noted that the periodicarray may take the form of any polygonal pattern, including, but notlimited to, a triangle, a square, or the like.

The microstructured cladding region 18, by way of the plurality ofcapillaries 22, includes a plurality of holes. The holes are preferablyelongated annular passages that extend substantially parallel to thelongitudinal axis of the fiber 14. The diameter of the holes may be, forexample, between 0.5 and 5.0 microns. The holes may be filled with a gasor another material that has a different index of refraction than thematerial surrounding the holes. As another alternative, there may be avacuum within the holes.

The hollow core region 20 generally comprises a lower refractive indexand the microstructured cladding region 18 comprises non-coaxial regionsof higher refractive index. Accordingly, the geometry of themicrostructured cladding region 18 and hollow core region 20 isconfigured to act as a quasi-two-dimensional photonic crystal with aphotonic bandgap that allows radiation of a select frequency range topropagate down the hollow core region 20, notably the propagation oflight at a wavelength of 1310 nm. In particular, light within the hollowcore region 20 is effectively trapped by the photonic band gap of thesurrounding material and geometry of the microstructured cladding region18, such that the light cannot propagate away from the core but ratherconstrained to travel along the axis of the fiber 14, substantiallyconfined to the hollow core region 14, as a guided mode.

FIG. 6 shows a preform of a plurality of elongate elements in the formof capillaries 100 suitable for use in forming a hollow-core opticalfiber 14 consistent with the present disclosure. FIG. 7 illustrates andexemplary apparatus for use in fabricating a hollow-core optical fiber14 from the preform illustrated in FIG. 6 .

As shown, a stack of an array of capillaries 100 is placed inside athick-walled silica glass tube 102. The silica glass tube 102 may formpart of the fiber 14 after drawing, serving as an outer cladding 24 (seeFIG. 4 ) to provide mechanical strength. During the drawing process, theinside of the tube 102 may be evacuated by sealing it within anevacuatable structure while the inside of some or all of the capillaries100 may be kept at a different and higher pressure, for example, becausethey are left open to the atmosphere. The evacuatable structure mayinclude, for example, a brass cylinder 104. Initially, it may be open atboth ends. The cylinder 104 may then be sealed to the tube 102 at oneend. The tube may then terminate within the brass cylinder 104. Some orall of the capillaries 100 may pass through the brass cylinder 104,which is then sealed around those capillaries that pass righttherethrough at the top of the cylinder 104. The brass cylinder 104 maythen be evacuated during the drawing process.

It should be noted that during the drawing process, in which the tube102 and the capillaries 100 are drawn downwardly from the brass tube104, the outer tube 104 does not collapse, despite being evacuated,because it has thick walls. In contrast, interstitial holes betweencapillaries 100, which are already smaller and have relatively thinboundaries defined by walls of the capillaries may collapse and thus maynot present in the final fiber, which may be desirable). Capillarieswhich are evacuated will also collapse completely if there is a higherpressure around the capillary. On the other hand capillaries which arefilled with atmospheric-pressure air may expand.

It should be noted that, in some embodiments, the method of fabricatinga hollow-core optical fiber consistent with the present disclosure mayinvolve individually pressurizing one or more capillaries from thepreform during the drawing of the fiber 14. For example, hoses may beattached to selected ones of the plurality of capillaries 100, in whichsuch hoses may be attached to pressure-controllers. During drawing ofthe fiber from the preform, the pressures inside selected capillaries,and thus the holes into which they are drawn, may be varied by varyingthe pressure produced by the external pressure-controllers in the hoses.Thus, in some embodiments, the holes produced in the microstructuredcladding region of the drawn fiber 14 may vary in their cross-sectionalareas both along the fiber and from hole to hole in fiber transversecross-sections. It should be noted that the pressure inside any givencapillary may be controlled via other means and is not limited to theuse of hoses. For example, specific chambers may be used during thedrawing process, in which selected exposed ends of selected capillariesmay be provided within a given chamber and the pressure within suchcapillaries may be controlled.

FIG. 8 is a block diagram illustrating a fiber optics network includinga hollow-core fiber optic cable 10 consistent with the presentdisclosure. As previously described, the fiber optic cable 10 isconfigured to be used with a fiber optics network of a communicationssystem for the transmission of telecommunications data. The fiber opticcable 10 may include at least one hollow-core optical fiber 14 encasedwithin a cable housing and optical fiber connectors coupled to ends ofthe hollow-core optical fiber 14 and configured to operably receive andtransmit light at a wavelength of 1310 nm. The optical fiber connector,for example, may include a small form factor (SFF) connector configuredto mechanically couple the hollow-core optical fiber to at least one ofan additional optical fiber and/or a device for transmitting and/orreceiving a light signal (e.g., communications equipment or the like).

Accordingly, the fiber optic cable 10 may be coupled at one end to afirst communications device/equipment 202 and coupled at a second end toa second communications device/equipment 204. Such devices/equipment mayinclude, for example, radios, switches, SFP Modules, and the like. Thefiber optic cable 10 is configured to receive a light signal from atleast the first communications device/equipment 202 and transmit, viathe hollow-core optical fiber 14, the light signal at a wavelength of1310 nm to the second communications device/equipment 204.

FIG. 9 is a flow diagram illustrating one embodiment of a method 300 fortransmitting telecommunications data utilizing the hollow-core opticalfiber. The method 300 includes providing a hollow-core optical fiberconfigured to support and guide the propagation of light at a wavelengthof 1310 nanometers (operation 310). The hollow-core optical fiberincludes a microstructured cladding region formed by at least some ofthe elongate elements and a hollow core region surrounded by themicrostructured cladding region and configured to guide optical energywithin the hollow core region by total internal reflection at aninterface between the hollow core region and the microstructuredcladding region, wherein the hollow core and microstructured claddingregions are configured to support and guide the propagation of light ata wavelength of 1310 nanometers. The method 300 further includesreceiving a light signal comprising telecommunications data (operation320). The light signal may be received from communicationsdevice/equipment or another optical fiber or other communicationconnection to which the hollow-core optical fiber is coupled. The method300 further includes transmitting, via the hollow-core optical fiber,the light signal (operation 330).

Accordingly, by providing a hollow-core optical fiber able to functionwithin the 1310 nm optical wavelength band, the benefits of hollow-coreoptical fibers can be realized in communication systems operating withinthe 1310 nm optical wavelength band. More specifically, the hollow-coreoptical fiber of the present invention would reduce latency andattenuation when used in telecommunications networks and applications,thereby enhancing the speed and distance capabilities beyond currentdesigns engineered around solid-core optical fibers. Furthermore, thefiber optic cable allows for the hollow-core optical fiber to be usedwith commercially available communications equipment (e.g., radios,switches, SFP Modules, etc.), and provide the advantages of ahollow-core optical fiber over the conventional solid-core opticalfibers.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments.

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equivalentsof the features shown and described (or portions thereof), and it isrecognized that various modifications are possible within the scope ofthe claims. Accordingly, the claims are intended to cover all suchequivalents.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

Various modifications of the invention and many further embodimentsthereof, in addition to those shown and described herein, will becomeapparent to those skilled in the art from the full contents of thisdocument, including references to the scientific and patent literaturecited herein. The subject matter herein contains important information,exemplification and guidance that can be adapted to the practice of thisinvention in its various embodiments and equivalents thereof.

1. A hollow-core optical fiber configured to support and guide thepropagation of light at a wavelength of 1310 nanometers, the hollow-coreoptical fiber comprising: a hollow core region surrounded by amicrostructured cladding region, wherein the hollow-core optical fiberis configured to guide the propagation of light within the hollow coreregion by total internal reflection at an interface between the hollowcore region and the microstructured cladding region such that a majorityof light transmitted through the hollow-core optical fiber travelswithin a gas or a vacuum of the hollow core region.
 2. The hollow-coreoptical fiber of claim 1, comprising wherein the hollow core andmicrostructured cladding regions are configured to support and guide thepropagation of light at a wavelength of 1310 nanometers.
 3. Thehollow-core optical fiber of claim 2, wherein the hollow core regioncomprises a lower refractive index and the microstructured claddingregion comprises non-coaxial regions of higher refractive index.
 4. Thehollow-core optical fiber of claim 3, wherein the microstructuredcladding region comprises a cladding material.
 5. The hollow-coreoptical fiber of claim 4, wherein the cladding material is positionedsubstantially symmetrically around the hollow core region.
 6. Thehollow-core optical fiber of claim 4, wherein the cladding material isarranged in a regularly spaced periodic array.
 7. The hollow-coreoptical fiber of claim 6, wherein the periodic array is configured in apolygonal lattice pattern.
 8. The hollow-core optical fiber of claim 7,wherein the periodic array is configured in a hexagonal lattice pattern.9. (canceled)
 10. (canceled)
 11. A method of fabricating a hollow-coreoptical fiber, the method comprising: assembling and forming a preformof plurality of elongate elements, at least some of the elongateelements comprising capillaries; and drawing the preform into ahollow-core optical fiber configured to support and guide thepropagation of light at a wavelength of 1310 nanometers, wherein atleast some of the elongate elements form a hollow core region and atleast some of the elongate elements form a microstructured claddingregion surrounding the hollow core region, the hollow-core optical fiberbeing configured to guide the propagation of light within the hollowcore region by total internal reflection at an interface between thehollow core region and the microstructured cladding region such that amajority of light transmitted through the hollow-core optical fibertravels within a gas or a vacuum of the hollow core region.
 12. Themethod of claim 11, wherein the hollow core and microstructured claddingregions are configured to support and guide the propagation of light ata wavelength of 1310 nanometers.
 13. The method of claim 12, wherein thehollow core region comprises a lower refractive index and themicrostructured cladding region comprises non-coaxial regions of higherrefractive index.
 14. The method of claim 13, wherein themicrostructured cladding region comprises a cladding material.
 15. Themethod of claim 14, wherein the cladding material is positionedsubstantially symmetrically around the hollow core region.
 16. Themethod of claim 14, wherein the cladding material is arranged in aregularly spaced periodic array.
 17. The method of claim 16, wherein theperiodic array is configured in a polygonal lattice pattern.
 18. Themethod of claim 17, wherein the periodic array is configured in ahexagonal lattice pattern.
 19. (canceled)
 20. (canceled)